Attachment plug cap and method of making the same



March 7, 1933. w c TREGONlNG 1,900,139

ATTACHMENT PLUG CAP AND METHOD OF MAKING THE SAME Filed Oct. 19, 1929Patented Mar. 7, 1933 UNITED WILL-mm c. rnneoiqme, or

me, or MILWAUKEE,

STATES ATTACHMENT. PLUG GAP wauwa'rosa, WISCONSIN,

wrsconsm,

ASSIGNOR TO CUTLER-HAMME A CORPORATION OF DELAWARE m manner on mxiNe rrmsum Applicatlon filed October 19, 1929. Serial No. 400,881.

to improvements in methods of mak- This invention relates attachmentplug caps and ing the same.

An object of the invention is to provide a method of making plug capswherein the use of molded in metal eyelets or inserts iseliminated,-thereby facilitating or speeding up production of the moldedpieces.

Another object is to minimize the number of metal parts required forproduction of a plug cap.

Another object is to facilitate assembly of the metal parts with respectto the mold ca V Another object is to provide a stronger and more rigidconnection between the meta parts and the insulating cap.

Another object is to provide a method of making plug caps wherein theshrinkage characteristics of the molded piece may be utilized as thesole means for effecting a rigid bond between the same andthe metalparts associated therewith.

Other objects and advantages tion will hereinafter appear.

The accompanying drawing illustrates certain embodiments of theinvention which will now be described, it being understood that theinvention is susceptible of modification in cerwithout departing from ofthe inventain details thereof the scope of the appended claims.

Referring to the drawing, Figure 1 is an enlarged bottom plan view of aplug cap constructed and assembled in accordance with my invention.

Fig. 2 is a vertical sectional view on the line 2-2 of Fig. 1. 7

Fig. 3 is a bottom plan view of the cold molded insulating piece priorto assembly of the combined contact and terminal members with respectthereto.

Fig. 4 is a plan view of one form of punched metal blank from which eachof the combined contact and terminal members may be produced.

' Fig. 5 is a perspective view of one combined contact and terminalmembers, tlia binding screw attached thereto, and

Figs. 6 and 7 are plan and fragmentary secof the with d comminutedasbestos 1 molded in metal eyelets or tional views, respectively, of amodified form of blank.

Referring first to Figs. 1, 2 and 3, the numeral 10 designates theinsulating body portion of a cap, and said body portion may comprise anysuitable or preferred composition which is adapted for cold moldingunder relatively heavy pressure while plastic and to be thereaftersubjected to the usual prolonged heat treatment for curing or hardening.Thus I may employ the well known cold molding composition whichcomprises a filler and a pitch binder.

Heretofore it has been customary to either provide within the insulatingbody a pair of inserts to which the contact and terminal members of thecap may be subsequently attached, or to mold in integral portions of thecontacts or terminal members themselves. However, the necessity forproviding molded in metal parts renders production of the molded piecescomparative-- 1y slow and tedious. By my improved method the necessityfor use of molded in metal parts or inserts is eliminated, whereby therate of production of the molded pieces by a single press may be greatlyincreased.

Thus as is well known the insulating material after cold molding thereofto the desired form is still somewhat plastic, or of a consistency knownin the cold molding art as mud. Also as is well known the usualprolonged heat treatment to which these cold molded pieces are subjectedfor curing or hardening thereof inherently results 1n a considerabledegree of shrinkage of the material of which the pieces are composed. Ihave discovered that it is possible to utilize this shrinkagecharacteristic of the cold molded material to provide for rigid andpermanent securement of a metal element pressed or inserted therewithinafter the moldlng operation and before the heat induration treatment.

Thus I preferably mold or otherwise form in the piece 10 a pair ofdiametrically opposed groups of recesses 11, 12 and 11", 12. Therecesses 12, 12 as shown may be circular and of a size to freelyaccommodate the shank of the usual binding screw. Recesses 11, 11"

llo

" receptacle ed piece in more positive engagement with the usual permitpassage of the wiring cord or conas shown may be of rectangular shape incross section, and the cross sectional dimensions thereof are preferablyslightly (say two thousandths of an inch) less than the correspondingdimensions of metal members or shanks 13, ltto be pressed or insertedthereinto.

The lower ends 13, 14 of said shanks are preferably slightly rounded toassist in guiding the same into said recesses, said shanks eing integralwith and bent downwardly at right angles from the portions 15 and 16respectively, which form the terminal plates of the plug cap. Alsointegral with said portions 15 and 16 and bent upwardly at right anglestherefrom are the portions 17 and 18, respectively, which form the jacksor blade contacts of the plug cap, said contacts being provided with theusual beveled upper ends and the usual perforations intermediate theends thereof for detachable interlocking engagement with the cooperatingcontacts of a (not shown). .Also as shown at 13", 14" in Figs. 2, 4 and5 the shanks 13, 14 are preferably provided with suitable notches .orindentations forming inwardly extending shoulders in the sides and edgesthereof for by the material of the insulating cap after shrinkage of thelatter.

As best illustrated in Fig. 2 the shanks 13 and 14 are presseddownwardly into the respective recesses 11 and 11 until the terminalplates 15 and 16 engage or rest upon the ledges 19 and 20 formed in theinsulating cap. The binding screws 21 and 22 are preferably threadedinto tapped openings in the terminal plates 15 and 16 prior to insertionof the shanks 13 and 14 into the aforementioned recesses, the shanks ofsaid screws being upset or staked as indicated at 21 (Fig.

to prevent subsequent entire removal of said binding screws.

' The molded insulating cap 10 is provided central perforation 23 toductors (not shown),the recesses 23, 23 being arranged to communicatetherewith for reception of the knot or other type of strain relievingmeans, and to permit attachment of the wires by leading the samedirectlyto the respective binding screws or by snubbing said wires around therespective contact jacks. The ledges 24 and 25 provide a seat for theusual thin fiber enclosing disk (not shown). The exterior surface of themolded cap may be of any desired contour, but the cap is preferably ofslightly tapered form and milled or otherwise roughened, as indicated at26 (Figs. 2 and 3) to facilitate gripping thereof by hand.

Withthe combined wcontact and terminal members assembled with respect tothe moldthe manner aforedescribed, the latter is subjected to the usualprolonged heat treatment for curing or hardening,

usual strain relieving.

whereupon it is found that the shrinkage effect aforementioned resultsin rigid and permanent securement of said metal parts with respect tothe insulating cap.

In the modified form .of blank shown in Figs. 6 and 7 the shank 27 ofthe combined contact and terminal member is provided with a pair ofspaced angular depressions or pockets 28 having horizontal or rightangular shoulders at the lower ends thereof, into which pockets theinsulating material is adapted to project upon insertion of the shankinto its corresponding recess, or as a result of the shrinkage of theinsulating material as aforestated.

By my improved method of making plug caps it will be noted that thecontact and terminal members may be formed of a single piece of metaland that the binding screw may be assembled and staked to the terminalmember in the first instance. The contact and terminal members arerigidly and permanently secured to the molded cap without the use ofmolded in eyelets or inserts and without the necessity for the usualriveting or upsetting operations incident to use of such additionalparts.

After the completely assembled caps have been heat treated for hardeningof the insulating material the same may be dipped or momentarilyimmersed in a suitable acid bath to clean the surfaces of the metalparts, including removal of any oxide which may have formed upon suchsurfaces as a result of the heat treatment.

While I prefer to provide notches or depressions of the characterillustratled for positive and cooperative engagement by the shrunkenwalls of the recesses, I have nevertheless demonstrated in practice thatthe slightly rough and irregular edges formed on the shanks by thepunching or shearing of the blanks will be sufliciently tightlyinterlocked with the shrunken walls of the recesses to resist orwithstand all pulling strains to which the parts of the cap willordinarily be subjected when in use.

Similarly, while I have shown but one form of molded insulating cap, itwill be understood that the form of the molded piece may be modified asin from the scope of the appended claims.

TVhat I claim as new and desire to secure by Letters Patent is:

1. The methodof making an attachment plug cap, which comprises coldmolding a mass of insulating material to form an article of the desiredshape, then pressing into the molded article an integral portion of acombined contact and terminal member, and

article to the usual shrinkage of the insulating material.

2. The method which comprises cold moldcombined conta an integral pro anarticle of the desired shape and providing said recess, said proj thinsai ing a mass of insulating materialto provide ing within said articlea recess of predetermined ly secured W1 5 size and shape, then insertingwithin said reof the walls of th cess a metal shank the cross sectionaldimenusual heat in-duration t sions of which are at least as great asthe ed cap.

cross sectional dimensions of said recess, and 7 As an ar thensubjecting said article to heat treatment tachment plug cap 10 forcuring whereby said shank is permanentsulating materi ly secured withinsaid recess by shrinkage of shape, said cap in by the molding ope termintion inserted tion being per d recess by con sult of the usual themolded cap, f said member carryhaving a recess nce for the the walls ofthe latter.

3. The method which comprises cold moldbined contact and ing a mass ofinsulating material to provide an integral proje a plug cap havingrecesses therein, thereafter recess, said proj e inserting within saidrecesses the integral cured within sai projecting shanks of combinedcontact and the walls of terminal members, then subjecting said cap heatindurationt to curing treatment to permanently secure the terminal saidshanks within said recesses through ing shrinkage of the walls of thelatter.

rovide a plug cap having diametrically of cold molded insula spacedpairs of recesses therein, thereafter having a recess formed insertingwithin certain of the recesses of ing each pair the integral projectingshanks of tact and terminal a pair of one-piece combined contact and ingan integ terminal members, said shanks having insaid recess and perwardly extending shoulders formed in the by shrinkage of thei surfacesthereof, and simultaneously insert- 9. An attachment p ing within theother recesses of each pair the insulating bo shanks of binding screwscarried by said terany kind, sai

minal members, then subjecting sa d cap to recesses forme the usual heattreatment for curing whereby eration, and

said first mentioned shanks are rigidly and bined contact an formedtherein 4. The method which comprises cold moldshank of said screw. inga mass of plastic insulatingmaterial to 8. In combination,

ct and terminal al co having a recess ration, a onethe latter as a rereatment of portion 0 and said cap to provide cleara on, and a one-piecmember, sa projecti manen dy molde d body h d therein by the moldingopof one-piece com- 1 members having d within said rea plurality dtermina permanently secured within their respective integral projectionsrecesses through contraction or distortion of cesses and shrinkage of ththe walls of the latter.

inserting within certain of the recesses of tion, a 4 each pair theintegral projecting shanks of to provi apair of one piece combinedcontact and terplate, minal members, said shanks having inwardbent npwarly extending shoulders formed in the surprovide a cont faces thereof,simultaneously inserting withtegral with said plate a in the otherrecesses of each pair the shanks at right angles the of binding screwscarried by said terminal tapped 0 members, then subjecting said cap tothe ususcrew having t al heat treatment for curing whereby said opening,

first mentioned shanks are rigidly and perto-preven manently securedwithin their respective resaid plate,

cesses through contraction or distortion of and said secon the walls ofthe latter, and thereafter subtaneously inserted i jecting at least themetal portions of the asbase prior to heat-in sembled cap to the actionof an acid bath to th latter,

- 11. An attachment 6. As an article of manufacture, an at-. h at-iduratabl insul tachment plug'cap comprising a body of ined free frominser sulating material cold molded to the desired having a p shape,said cap having a recess formed theremined cross-sec in by the moldingoperation, and a one-piece therein by the mo 60 clean the surfacesthereof.

permane ntly e materia 5. The method which comprises cold mold- 10. Incombination, ing a mass of plastic insulating material to cold moldedand heat (1 therein by d sheet me de a horizontally e an arm integr dlyat r act blade, a se nd bent do reto, herethrough, hreaded engageme fsaid screw aration thereof t end of said screw d arm being simuldrecesses in the duration treatment of t complete sep and the upse dmentione tso tional lding operation,

d recess by e latter as a member havd within being permanentcontractiont of the of the moldticle of manufacture, an atcomprising a ld molded tobody of inthe desired formed therepiece comer having within saidmanently setraction of a pre-formed plug cap ting material, said captherein by the mol e combined conid memberhavnserted within tly retainedtherein 'nsulating material.

lug cap comprising an d free from inserts of aving a plurality of dtherein by l of said body.

-formed base of ble insulating having a plurality of rethe moldingoperatal member formed xtending terminal th said plate and es thereto tocond arm inwnwardly e having a a binding nt with said being upset from pcomprising a body cold moldnd, said body of recesses ofpredeterdimensions formed a plurality scribed my name.

WILLIAM C. TREGONING.

